Saving the Integrated File System using multiple devices for a single save operation

 

A traditional save to a single device produces one tape file on the tape media. You can perform a save operation while using more than one media devices simultaneously.

Integrated File System data saved by a single SAV command using multiple devices will be in a parallel save format. The data is spread across the media devices. If you use Backup, Recovery and Media Services (BRMS), the save format is also parallel.

Using a media definition to save your Integrated File System data to a single device specified in a *MEDDFN is the same as specifying that device on the SAV command. It is not beneficial to use a *MEDDFN when saving to a single device. The data is saved in serial format.

Table 1. Integrated File System parallel saves
Save scenario Using SAV command Using BRMS
Save integrated file systems to multiple devices Parallel Parallel

This table shows the correlation between the Integrated File System being saved and the name of the media files being produced.

Table 2. Integrated File System saved
Data saved Number of devices Format Tape media files produced
Integrated File System data 1 Serial SAVdatetime
Integrated File System data 2 Parallel Device 1: SAVdatetime Device 2: SAVdatetime

Once you create a media definition, a convenient way to save the entire Integrated File System to multiple devices is to specify SAV DEV (’/QSYS.LIB/Y.LIB/X.meddfn’) OBJ ((’/*’) (’/QSYS.LIB’ *OMIT) (’/QDLS’ *OMIT).

Backup Recovery Media Services/400 (BRMS) provides an easy to use interface that allows you to perform parallel save operations without creating a media definition. You specify which tape devices to use in parallel, and BRMS builds and manages the media definition for you.

  1. Performing a parallel save with large objects may improve performance. However, if saving small objects, the performance may decrease.

  2. Restoring individual objects from a parallel save may take a substantial amount of time.

 

Parent topic:

Saving to multiple devices to reduce your save window